The present invention relates to thin film magnetic structures. In particular, the present invention pertains to a thin film inductive write head.
Numerous inductive head formation processes are well known in the art. Unfortunately, many of these conventional inductive head formation processes are limited to use with only certain materials. That is, typical prior art inductive head formation processes utilize only materials having physical properties and characteristics which are conducive to manufacturing conditions and parameters associated with such prior art inductive head formation processes. For example, U.S. Pat. No. 5,283,942 to Chen et al. recites the use of a sacrificial layer in planarization schemes to generate narrow write trackwidth devices through the use of staggered poles or subtractive etching of a multi-layered pole structure. In the former case, this sacrificial layer is removed to the write gap and the P2 pole is staggered so as to fill only a portion of the resultant cavity. In the latter case, the sacrificial layer is removed only to the upper surface of an initial P2 pole layer, and a key feature of the claimed structure is the substantially equal width of the P1 and P2 poles at the write gap in conjunction with a substantially vertical profile of each. With use of ion milling to provide a self-aligned pole structure with P1 and P2 of substantially equal width at the write gap, progressively greater removal of the shield 2 is experienced with distance from the P1 pole as the desired step of 2 or more write gap lengths at the P1 pole is generated. Limiting such removal to an acceptably small range is one of the primary obstacles to successful use of this approach. This can prevent the use of such a process as the designed separation of the read sensor from the write gap is reduced to minimize the positional offset of read and write functions when the head is not positioned with the read and write transducers aligned tangential to the data track (as when a rotary actuator is used).
Further, U.S. Pat. No. 5,285,340 to Ju et al. recites the use of a chemical etching process to produce a cavity on a patternable dielectric material. This cavity is substantially filled by electroplating a first pole layer, a non-magnetic write gap, and a second pole layer. A final P2 element is stitched in to the remaining cavity to complete the transducer. Again, a key feature of the claims is the substantially equal width of the P1 and P2 poles at the write gap in conjunction with a substantially vertical profile of each. Write gap thickness is typically in the range of 1000-5000 angstroms and it is desirable to control this to a tolerance of approximately 200 angstroms or better. Measurement and control of a plated write gap in such an approach can complicate the process requirements for the device or limit the range of the application of this technique as such tight control of thin plated layers can be difficult.
Additionally, U.S. Pat. No. 4,947,541 to Toyoda et al. recites a method for producing a thin film head. The thin film head formation processes of the Toyoda et al. reference utilize conventional core formation materials. Specifically, the Toyoda et al. reference explicitly recites using conventional permalloy (NiFe) to form the upper and lower cores of a thin film head. Further, the Toyoda et al. reference recites forming the upper core of the thin film head using conventional electroplating techniques.
Prior art thin film head formation processes, such as the processes described in the above-mentioned Toyoda et al. reference, are not well suited for use with materials having high magnetic field saturation (HBsat) characteristics. HBsat materials are ideally suited for forming the upper and lower cores of a thin film inductive head. However, most HBsat materials cannot be formed into upper or lower cores using typical fabrication methods. As an example, many HBsat materials have physical characteristics rendering them unsuited for electroplating processes. Thus, such HBsat materials could not be effectively used, in the manner recited in the Toyoda et al. reference, to form the upper core of a thin film inductive head.
Thus, a need has arisen for a thin film head formation method which is not limited to use only with conventional core formation materials. A further need exists for a thin film head and a thin film head formation method which utilize advantageous HBsat materials. Still another need exists for a thin film head formation method which utilizes advantageous HBsat materials but which does not suffer from increased magnetostriction associated with conventional HBsat materials.
The present invention provides a thin film head formation method which is not limited to use only with conventional core formation materials. The present invention further provides a thin film head and a thin film head formation method which utilize advantageous HBsat materials. The present invention also provides a thin film head formation method which utilizes advantageous HBsat materials but which does not suffer from increased magnetostriction associated with conventional HBsat materials.
More specifically, in one embodiment, the present invention recites forming a cavity in a dielectric layer. Next, a layer of high magnetic field saturation (HBsat) material is sputter-deposited over the dielectric layer such that the HBsat material is deposited into the cavity formed in the dielectric layer. The cavity in the dielectric layer functions as a mold or xe2x80x9cstencilxe2x80x9d for the HBsat material. The HBsat material deposited into the cavity is used to form the first core of a thin film head. After the formation of the first core of the thin film head, a gap layer of material is deposited above the dielectric layer and above the first core. Next, a layer of HBsat material is sputter-deposited above the gap layer of material and above the first core of the thin film head. The layer of HBsat material sputter-deposited above the gap layer of material and above the first core is used to form the second core of the thin film head. Hence, this invention forms first and second cores of a thin film head using sputter-deposition processes. As a result, selected HBsat materials which were not well suited to conventional thin film head formation methods can now be used to form the cores of thin film head structures.
In other embodiments, the present invention specifically recites the formation of the above-mentioned cavity in the dielectric layer. In one such embodiment, the present invention first surrounds a sacrificial metal structure with the above-mentioned dielectric layer. Next, the present embodiment removes the sacrificial metal structure. In so doing, an opening remains in the dielectric layer. In this embodiment, the opening defines the cavity in the dielectric layer.
These and other advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments which are illustrated in the various drawing figures.